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Mon, 07 Sep 2026 08:14:04 +0000 X-Mizu-Trace-ID: e2e364529cd50751 X-Migadu-Flow: FLOW_OUT From: Ye Liu To: Oleg Nesterov , "Peter Zijlstra (Intel)" , Marco Elver , Ye Liu , Tejun Heo , Christian Brauner , Bart Van Assche , Yi Tao Cc: Michal Hocko , paulmck@kernel.org, mingo@redhat.com, rostedt@goodmis.org, jpoimboe@kernel.org, mic@digikod.net, tglx@kernel.org, akpm@linux-foundation.org, david@kernel.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, rafael@kernel.org, gnoack3000@gmail.com, ljs@kernel.org, sj@kernel.org, rientjes@google.com, shakeel.butt@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, will@kernel.org, boqun@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com, josh@joshtriplett.org, urezki@gmail.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, tony.luck@intel.com, reinette.chatre@intel.com, x86@kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, pavel@kernel.org, lance.yang@linux.dev, mhiramat@kernel.org, pmladek@suse.com, longman@redhat.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, mark.rutland@arm.com, Dave.Martin@arm.com, james.morse@arm.com, babu.moger@amd.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rcu@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v2 1/8] sched: introduce for_each_process_rculock and for_each_thread_rculock Date: Mon, 7 Sep 2026 16:13:27 +0800 Message-Id: <20260907081334.1152889-2-ye.liu@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260907081334.1152889-1-ye.liu@linux.dev> References: <20260907081334.1152889-1-ye.liu@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AFF6F1C0003 X-Stat-Signature: jmhojqxi55ran1jfsz9ss4yuwfdx4otj X-HE-Tag: 1788768846-871670 X-HE-Meta: U2FsdGVkX1/z/bpKclO1SJj1S8ejJ3GvGPqPtFDEY38fpdgwwmZw4kXDClSTTs92RkSbcUNzQA7gHQTjfLvds98cKL5AbYsuB9n35MZVDDgCl2MwIMmNwK6iLM/1rJHMLHSaOAFGS2nh11PFNEs5X/0eN1cTCRhokXMF7sKCdTkmQm7kPunH15wb+sTdVF2/9SEWtOOVHBksS/Kw4RDvp9m++gfGlKbHd8urQnxTxwoKytYmd6n8frdTQj/DlZ+MA9u+nDMelq2zVJyooviNlwF6py6q3dZHb5h1FaLRWhwKPxicyriU/nXgnMoH5XQDCp2/1eNmFJ7I2+PpzGn1SmCBjyBdGtaVTBbIUSjZwSJn8num+zN2PqctaSpb0EESy8CV5Lb2hyWXLhh9tUME9pL6r9cIiEDt6GPAozpIJd7aAdZxpbnzstjUx13gXk3HpBu4XMLrPCSBU2WTVmxsuRUwhWjwaDnV1bpommd9UecXVWf18e81zVWK0znBy0cnYomXxhPsJ5Dkb8yFyruiV+5s/smdtOkks/MdPthdCURdsSPgJtsBZevkEwQCp46Eh76WpztbIx9asCFBIAVsWF5rjG9G4xcTD1vYUbJiySAOVeT70vRGWIoeufhWS28+5AVnCDL/PjGg8lDeUzMIo0bncwkwoPOTMXw3jp4TJRuZpzMlShrs7kcmz4gJrVQbmuNHGjSbhUhLTP7dC13qJilNHnFtTMk9h4AciOsvQ2JUILS1Bj+/zAFeyK5PQtL79OCY5ERDZVwkmCo51A6bx4xUC8+I6GGwvf6ZsVPC3F6TTar5ZC+BVbTXS4FVM9zCKL8nTjYNPCr6XyXekIF0IcrLTXgjCkOV2EBzu1OpRX9ygcrunNjKJ1UqzcP938hTUTpcxnha0+GBTvrxH6DZympaQBdSp7G9/mi2iakcNa4R4jGIfbSXRWajylVfVSg6RJBN+lvl4pWrD7LFz5K u5GDHm3A vFU9EmRCDD4GtCDWqbh4XutjiKZrOMnvvpyezixY9jOD7StGBYE1S6jvgPcI34DMDJCjz6IgCAcK8FzahLv4vZHaH9Y+fiGKHenDk+6rsuzIg0QxUkz8UykD/8Cv7jwVNzlLnFBAUdE5cPTOemphXhEW/eoHVuClV/UOY52kwWuiVZ/N7nQxc8TAnLvFUV0G55aPqPMAX5okd4Pu4JWqxcLI/Bhly4HJqr84c3A8w2njuUQCmVXpTDh66nOl2SXKpZvNjBHeER+W8uq9BA2TXAsTq8iyr9zapkuNZLI6bAZDRqFVM5Py2Drph3Bn5gDWdNSqGOvThQ/t1ATyv+H08w4ACUjoM6YcorUD0rQxx6tydvUKSCog0kh5w7c5lFo5DL63T5qoRc8FYMxlAtq51U4IQLmgunXUAa/TFaZI6HvLWkif/RCoR3FnywXthxZXTrS8k Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ye Liu Introduce for_each_process_rculock(), for_each_thread_rculock() and for_each_process_thread_rculock() macros that acquire the RCU read lock before the iteration starts and release it when the loop is left, so that the RCU read-side critical section is scoped to the loop body instead of an externally managed rcu_read_lock()/rcu_read_unlock() pair. Signed-off-by: Ye Liu Acked-by: Michal Hocko --- Changes in v2: - Rename macros from *_rcu to *_rculock (Steven Rostedt, Thomas Gleixner) - Improve comment on for_each_process_thread_rculock() double loop - Change prefix from mm: to sched: (Michal Hocko) include/linux/sched/signal.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 584ae88b435e..110ea9f131f3 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -2,6 +2,7 @@ #ifndef _LINUX_SCHED_SIGNAL_H #define _LINUX_SCHED_SIGNAL_H +#include #include #include #include @@ -663,6 +664,30 @@ extern bool current_is_single_threaded(void); #define for_each_process_thread(p, t) \ for_each_process(p) for_each_thread(p, t) +/* + * Variants of for_each_process(), for_each_thread() and + * for_each_process_thread() that automatically acquire and release the + * RCU read lock via scoped_guard(rcu). The lock is held for the + * duration of the loop and released on exit, including via break, + * goto, or return. + */ +#define for_each_process_rculock(p) \ + scoped_guard(rcu) \ + for (p = &init_task ; (p = next_task(p)) != &init_task ; ) + +#define for_each_thread_rculock(p, t) \ + scoped_guard(rcu) \ + __for_each_thread((p)->signal, t) + +/* + * Double loop: 'break' only exits the inner for_each_thread() loop. + * Use 'goto' to exit both loops; the RCU read lock is released + * automatically when the scoped_guard scope is left. + */ +#define for_each_process_thread_rculock(p, t) \ + scoped_guard(rcu) \ + for_each_process(p) for_each_thread(p, t) + typedef int (*proc_visitor)(struct task_struct *p, void *data); void walk_process_tree(struct task_struct *top, proc_visitor, void *); -- 2.25.1